Electric vehicles use roughly a third of the energy so that 30 PWh only needs to be an extra 10 PWh for the grid. We need to increase overall capcity by 50%.
I doubt that; PV is cheap compared to storage, so it makes more sense to install twice as much PV as needed and include the charging plugs in existing car parks (and waste some power during commuting and lunch breaks), than to add enough immobile storage to allow most car charging to happen at night.
Only when the power doesn’t come from PV. If it does, you need (three?) times as much battery capacity: the car’s battery, the immobile battery that the car charges from, and the battery which powers your houses (and some industry and commerce) overnight. If you charge your cars during the day, you can use some of the battery capacity in the electric cars, partially discharging some of them overnight to supply your nighttime needs.
Chances are the network isn’t used at full capacity, so if people are willing to charge their cars outside peak hours (e.g, between midnight 7 AM, we wouldn’t need 50% more, network wise.
